Battery pack bus bar assembly with shaped interconnect mounting platforms

ABSTRACT

A battery assembly utilizing a compact and robust bus bar configuration is provided. The batteries within the assembly are divided into groups with each group formed from at least two rows of batteries. The batteries within each battery group are connected in parallel and the groups are connected in series. The batteries are interconnected using a plurality of non-overlapping bus bars configured in an alternating pattern with the plurality of battery groups, where each of the bus bars includes multiple interconnect mounting platforms. The interconnect mounting platforms simplify coupling multiple rows of batteries to each bus bar while minimizing bus bar current density variations and insuring that individual interconnect resistance remains relatively low and at about the same level per battery.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/057,169, filed 1 Mar. 2016, the disclosure of which isincorporated herein by reference for any and all purposes.

FIELD OF THE INVENTION

The present invention relates generally to battery packs and, moreparticularly, to a robust and compact design for a battery assembly busbar interconnect system.

BACKGROUND OF THE INVENTION

In response to the demands of consumers who are driven both byever-escalating fuel prices and the dire consequences of global warming,the automobile industry is slowly starting to embrace the need forultra-low emission, high efficiency cars. One of the most commonapproaches to achieving a low emission, high efficiency car is throughthe use of a hybrid drive train in which an internal combustion engineis combined with one or more electric motors. An alternate approach thatis intended to reduce emissions even further while simultaneouslydecreasing drive train complexity is one in which the internalcombustion engine is completely eliminated from the drive train, thusrequiring that all propulsive power be provided by one or more electricmotors. Regardless of the approach used to achieve lower emissions, inorder to meet overall consumer expectations it is critical that thedrive train maintains reasonable levels of performance, range,reliability, and cost.

Irrespective of whether an electric vehicle (EV) uses a hybrid or anall-electric drive train, the battery pack employed in such a carpresents the vehicle's design team and manufacturer with varioustrade-offs from which to select. For example, the size of the batterypack affects the vehicle's weight, performance, driving range, availablepassenger cabin space and cost. Battery performance is anothercharacteristic in which there are numerous trade-offs, such as thosebetween power density, charge rate, life time, degradation rate, batterystability and inherent battery safety. Other battery pack design factorsinclude cost, both per battery and per battery pack, materialrecyclability, and battery pack thermal management requirements.

In order to lower battery pack cost and thus the cost of an EV, it iscritical to reduce both component cost and assembly time. An area ofpack fabrication that has a large impact on assembly time, especiallyfor large packs utilizing small form factor batteries, is the procedureused to connect the batteries together, where the batteries aretypically grouped together into modules which are then interconnectedwithin the pack to achieve the desired output power. In a conventionalpack, the high current interconnects that electrically connect eachterminal of each battery to the corresponding bus bar are typicallycomprised of wire, i.e., wire bonds. Unfortunately wire bonding is avery time consuming, and thus costly, process and one which mayintroduce reliability issues under certain manufacturing conditions.

Accordingly, what is needed is a robust interconnect system that allowsthe battery pack to be quickly and efficiently assembled, thus loweringmanufacturing time and cost. The present invention provides such aninterconnect system.

SUMMARY OF THE INVENTION

The present invention provides a battery assembly comprising (i) aplurality of batteries divided into rows, where each battery includesboth a first terminal and a second terminal accessible at a first endportion of the battery, where the plurality of batteries are dividedinto a plurality of battery groups, where each battery group iscomprised of at least two rows of batteries, where the batteries withineach battery group are electrically connected in parallel, and where thebattery groups are electrically connected in series; and (ii) aplurality of non-overlapping bus bars, preferably of uniform thickness,configured in an alternating pattern with the plurality of batterygroups, where the alternating pattern alternates a single bus bar with asingle battery group. Each single bus bar of the plurality ofnon-overlapping bus bars includes (i) a first plurality of interconnectmounting platforms extending at a first non-perpendicular angle from afirst edge of the single bus bar, where each of the first plurality ofinterconnect mounting platforms is arcuately shaped, where each of thefirst plurality of interconnect mounting platforms is electricallyconnected to a first subset of the plurality of batteries via the firstterminals of the first subset of the plurality of batteries, and wherethe first subset of the plurality of batteries is comprised of at leastfour batteries; (ii) a second plurality of interconnect mountingplatforms extending at a second non-perpendicular angle from a secondedge of the single bus bar, where each of the second plurality ofinterconnect mounting platforms is comprised of an initial platformportion extending from the second edge of the single bus bar and a pairof platform extensions extending from the initial platform portion,where the initial platform portion is electrically connected to a secondsubset of the plurality of batteries via the second terminals of thesecond subset of the plurality of batteries, where the second subset ofthe plurality of batteries is comprised of at least one battery, where afirst platform extension of the pair of platform extensions iselectrically connected to a third subset of the plurality of batteriesvia the second terminals of the third subset of the plurality ofbatteries, where the third subset of the plurality of batteries iscomprised of at least one battery, where a second platform extension ofthe pair of platform extensions is electrically connected to a fourthsubset of the plurality of batteries via the second terminals of thefourth subset of the plurality of batteries, where the fourth subset ofthe plurality of batteries is comprised of at least one battery.

In one aspect, preferably each of the first plurality of interconnectmounting platforms extending from the first edge of the single bus barextends beyond a first plane, where the first plane is located midwaybetween the single bus bar and a first adjacent bus bar, where the firstadjacent bus bar is adjacent to the first edge of the single bus bar,and where each of the second plurality of interconnect mountingplatforms extending from the second edge of the single bus bar extendsbeyond a second plane, where the second plane is located midway betweenthe single bus bar and a second adjacent bus bar, where the secondadjacent bus bar is adjacent to the second edge of the single bus bar.

In another aspect, the first plurality of interconnect mountingplatforms and/or the second plurality of interconnect mounting platformsmay be fixed to an underlying structure. The underlying structure may becomprised of an electrical insulator positioned between the plurality ofbatteries and the plurality of non-overlapping bus bars. The underlyingstructure may be comprised of a battery separator structure. Eachinterconnect mounting platform may include a mounting aperture, therebyallowing each interconnect mounting platform to be fixed to theunderlying structure via the mounting aperture. Each interconnectmounting platform may be fixed to the underlying structure using atechnique selected from bonding, staking, clamping or pinning.

In another aspect, the first battery terminal of each battery of theplurality of batteries may be comprised of a crimped edge regionintegral to the battery casing corresponding to each battery of theplurality of batteries. The second battery terminal of each battery ofthe plurality of batteries may be comprised of a large contact areaterminal nub integrated into a central region of the battery capassembly.

In another aspect, each bus bar of the plurality of non-overlapping busbars may further comprise (i) a first plurality of wire bond or ribboninterconnects, where each of the first plurality of interconnectmounting platforms is electrically connected to the first subset of theplurality of batteries by the first plurality of wire bond or ribboninterconnects and (ii) a second plurality of wire bond or ribboninterconnects, where each of the second plurality of interconnectmounting platforms is electrically connected to the second, third andfourth subsets of the plurality of batteries by the second plurality ofwire bond or ribbon interconnects.

In another aspect, the battery assembly may further comprise anelectrical insulator positioned between the plurality of batteries andthe plurality of non-overlapping bus bars. The electrical insulator maybe comprised of a tray member, where the plurality of non-overlappingbus bars are attached to an upper surface of the tray member, and wherethe tray member includes a plurality of apertures that provide access tothe first and second terminals of the plurality of batteries.Alternately, the electrical insulator may be comprised of anelectrically insulative layer attached to a lower surface of at least aportion of the plurality of non-overlapping bus bars.

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

It should be understood that the accompanying figures are only meant toillustrate, not limit, the scope of the invention and should not beconsidered to be to scale. Additionally, the same reference label ondifferent figures should be understood to refer to the same component ora component of similar functionality.

FIG. 1 provides a schematic diagram of a battery pack with bus barsabove and below the battery cells in accordance with the prior art;

FIG. 2 provides a schematic diagram of a battery pack with both bus barsadjacent to one end of each of the battery cells in accordance with theprior art;

FIG. 3 provides a detailed perspective view of the bus bars in aparticular layer stack configuration in accordance with the prior art;

FIG. 4 provides a top view of a battery module utilizing a series ofnon-overlapping bus bars of alternating polarity in accordance with theprior art;

FIG. 5 provides a schematic diagram of a battery pack utilizing aplurality of the battery modules shown in FIG. 4 combined in a seriesconfiguration;

FIG. 6 provides a schematic diagram of a battery pack utilizing aplurality of the battery modules shown in FIG. 4 combined in a parallelconfiguration;

FIG. 7 provides a perspective view of a portion of a battery module suchas that shown in FIG. 4;

FIG. 8 provides a perspective view of the same portion of the batterymodule as shown in FIG. 7, with the upper tray member as well as thebatteries removed;

FIG. 9 provides a top view of a battery module utilizing a series ofnon-overlapping bus bars with the interconnect mounting platforms of thepresent invention;

FIG. 10 provides a top view of the battery module shown in FIG. 9 withthe inclusion of an electrically non-conductive separator interposedbetween the bus bar assembly and the batteries;

FIG. 11 provides a top view of the battery module shown in FIG. 9 withthe inclusion of an electrically non-conductive separator layer attachedto the lowermost surface of the bus bar assembly;

FIG. 12 provides additional detail regarding the location of aninterconnect mounting platform relative to the underlying batteries;

FIG. 13 provides a top view of a battery module utilizing a series ofnon-overlapping bus bars with interconnect mounting platforms configuredin accordance with an alternate preferred embodiment of the invention;

FIG. 14 provides a top view of the battery module shown in FIG. 13 withthe inclusion of an electrically non-conductive separator interposedbetween the bus bar assembly and the batteries;

FIG. 15 provides a top view of the battery module shown in FIG. 13 withthe inclusion of an electrically non-conductive separator layer attachedto the lowermost surface of the bus bar assembly; and

FIG. 16 provides additional detail regarding the location of aninterconnect mounting platform relative to the underlying batteries.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises”, “comprising”, “includes”, and/or“including”, as used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features, processsteps, operations, elements, components, and/or groups thereof. As usedherein, the term “and/or” and the symbol “/” are meant to include anyand all combinations of one or more of the associated listed items.Additionally, while the terms first, second, etc. may be used herein todescribe various steps, calculations or components, these steps,calculations or components should not be limited by these terms, ratherthese terms are only used to distinguish one step, calculation orcomponent from another. For example, a first calculation could be termeda second calculation, and, similarly, a first step could be termed asecond step, without departing from the scope of this disclosure.

In the following text, the terms “battery”, “cell”, and “battery cell”may be used interchangeably and may refer to any of a variety ofdifferent battery configurations and chemistries. Typical batterychemistries include, but are not limited to, lithium ion, lithium ionpolymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickelzinc, and silver zinc. The term “battery pack” as used herein refers toan assembly of batteries electrically interconnected to achieve thedesired voltage and capacity, where the battery assembly may becontained within a battery pack enclosure. The terms “electric vehicle”and “EV” may be used interchangeably and may refer to an all-electricvehicle, a plug-in hybrid vehicle, also referred to as a PHEV, or ahybrid vehicle, also referred to as a HEV, where a hybrid vehicleutilizes multiple sources of propulsion including an electric drivesystem.

FIG. 1 illustrates a portion of an exemplary battery pack 100 utilizinga conventional battery pack configuration in which the batteryinterconnects (e.g., wire bonds) are attached to both the upper andlower portions of the batteries. As shown, battery pack 100 includes afirst group of batteries 102 and 104 connected in parallel, a secondgroup of batteries 106 and 108 connected in parallel, and a third groupof batteries 110 and 112 connected in parallel. The first, second andthird groups of batteries are connected in series. Bus bars 114, 116,118, 120, 122, 124 are used to connect the batteries in this paralleland series arrangement. Each of the bus bars is coupled to therespective batteries with one or more interconnects 125 (e.g., wirebonds). A relatively thick wire 126 couples the second bus bar 114 tothe third bus bar 122, making a series connection between the first andsecond battery groups, while a second relatively thick wire 128 couplesthe fourth bus bar 116 to the fifth bus bar 124, making a seriesconnection between the second and third battery groups. As a result, thefirst bus bar 120 is the negative terminal while the sixth bus bar 118is the positive terminal for battery pack 100.

The use of bus bars at both ends of the batteries as illustrated in FIG.1 requires a relatively complex manufacturing process in order to (i)attach the battery interconnects 125 between the battery end surfacesand the bus bars, and (ii) attach the wires (e.g., wires 126 and 128)that couple the upper bus bars to the lower bus bars. Wires 126 and 128are also problematic in the sense that they can introduce parasiticresistance into the current path, which in turn can introduce a voltagedrop under high current drain conditions. Additionally thisconfiguration prevents, or at least limits, the ability to efficientlyremove battery pack heat by affixing a heat sink to a battery endsurface.

FIG. 2 illustrates a portion of a battery pack 200 utilizing analternate battery pack configuration in which all the bus bars areproximate to one end of the battery pack, thus enabling efficient heatremoval from the other end of the battery pack. Furthermore, by locatingbus bars 214, 216, 218 and 222 proximate to one end of the batteries,fewer bus bars are required than in battery pack 100. The relativelythick wires 126 and 128 from the upper bus bars to the lower bus barsare also eliminated in the embodiment shown in FIG. 2.

Access to both the positive and negative terminals in battery pack 200is at one end of the cells, i.e., at the top end of the cells, where thebus bars are coupled to the positive and negative terminals usingbattery interconnects (e.g., wire bonds). As in the prior arrangement,the first group of batteries 102 and 104 are connected in parallel, thesecond group of batteries 106 and 108 are connected in parallel, and thethird group of batteries 110 and 112 are connected in parallel. Thefirst, second and third groups of batteries are connected in series. Busbars 214, 216, 218, 222 are used to couple the batteries in thisparallel and series arrangement. Specifically, starting with thenegative terminal of battery pack 200, a first bus bar 214 is connectedto the negative terminals of the first group of batteries 102 and 104while a second bus bar 222 is connected to the positive terminals of thesame group of batteries 102 and 104, both at the top end portion 138 ofeach of the batteries. The first and second bus bars 214 and 222 couplethe first group of batteries 102 and 104 in parallel. Similarly, thesecond bus bar 222 and the third bus bar 216 couple the second group ofbatteries 106 and 108 in parallel, while the third bus bar 216 and thefourth bus bar 218 couple the third group of batteries 110 and 112 inparallel. Series connections between battery groups are formed by thebus bars, specifically the second bus bar 222 connects the positiveterminals of the first group of batteries 102 and 104 to the negativeterminals of the second group of batteries 106 and 108; and the thirdbus bar 216 connects the positive terminals of the second group ofbatteries 106 and 108 to the negative terminals of the third group ofbatteries 110 and 112. The fourth bus bar 218 is the positive terminalof the battery pack 200.

In battery pack 200 the bus bars are arranged in a layer stack 250. Inthis stacking arrangement first bus bar 214 and third bus bar 216, whichare separated by an air gap or other electrical insulator to preventshort circuiting, are placed in a first layer 230. Similarly, second busbar 222 and fourth bus bar 218, which are also separated by a gap orinsulator, are placed in a third layer 234. Disposed between layers 230and 234 is an electrically insulating layer 232. To simplifyfabrication, the layer stack may be formed using layers of a circuitboard, e.g., with the bus bars made of (or on) copper layers or othersuitable conductive metal (such as aluminum) and the insulating layermade of resin impregnated fiberglass or other suitable electricallyinsulating material.

The batteries shown in FIGS. 1 and 2, as well as the batteries used inthe preferred embodiment of the invention, have a projecting nub as apositive terminal at the top end of the battery and a can, also referredto as a casing, that serves as the negative battery terminal. Thebatteries are preferably cylindrically shaped with a flat bottom surface(e.g., a battery utilizing an 18650 form factor). Typically a portion ofthe negative terminal is located at the top end of the cell, for exampledue to a casing crimp which is formed when the casing is sealed aroundthe contents of the battery. This crimp or other portion of the negativeterminal at the top end of the battery provides physical and electricalaccess to the battery's negative terminal. The crimp is spaced apartfrom the peripheral sides of the projecting nub through a gap that mayor may not be filled with an insulator.

Preferably in a battery pack such as battery pack 200 in which thebattery connections are made at one end of the cells (e.g., end portions138), a heat sink 252 is thermally coupled to the opposite end portions140 of each of the batteries. This approach is especially applicable toa co-planar battery arrangement which provides a relatively flat surfaceto attach a heat sink. Heat sink 252 may be finned or utilize air orliquid coolant passages. If heat sink 252 is air cooled, a fan may beused to provide air flow across one or more heat sink surfaces. In someconfigurations, heat sink 252 may be attached or affixed to the bottomof a battery holder.

In a typical battery pack in which all battery interconnects areattached to one end of the cells, typically a multi-layer stack (e.g.,stack 250) is used in order to provide bus bars for both terminals aswell as a suitable insulator located between the bus bars. This approachresults in a relatively complex bus bar arrangement. For example, FIG. 3from co-assigned U.S. patent application Ser. No. 14/203,874, thedisclosure of which is incorporated herein for any and all purposes,illustrates a multi-layer bus bar configuration in which the bus barsare stacked with an interposed insulator, and in which each bus barincludes multiple contact fingers 301.

In order to simplify bus bar design and configuration, therebysignificantly reducing material and fabrication costs as well as overallbattery pack complexity, the battery pack of the present invention mayutilize a series of non-overlapping bus bars of alternating polarity.Such a configuration is disclosed in co-assigned U.S. patent applicationSer. No. 14/802,207, filed 17 Jul. 2015, the disclosure of which isincorporated herein for any and all purposes. Although this approach maybe used throughout the entire battery pack, preferably it is used toform battery modules, where the battery modules are then electricallycoupled to form the battery pack. Assuming the battery pack is used inan electric vehicle as preferred, the individual battery modules may becontained within a single battery pack enclosure, or within multipleenclosures, the latter approach allowing subsets of modules to bedistributed throughout the vehicle in order to obtain a particularweight distribution or to fit within the confines of a particularvehicle envelope or structure.

FIG. 4 provides a top view of a battery module 400 utilizing a series ofnon-overlapping bus bars of alternating polarity in accordance with theprior art. Visible in FIG. 4 is the end portion of each of a pluralityof batteries 401, where the end portions are accessible throughcorresponding apertures in an upper tray member 403. Tray member 403 isprepared and/or treated to provide electrical isolation between thebatteries, for example by fabricating the tray member from anelectrically insulative material such as a plastic, or coating the traymember with an electrically insulative material. The batteries aredivided into a plurality of rows 405, where each row 405 includessixteen batteries 401. Even though module 400 is shown with seven rows405, it should be understood that this design is not limited toconfigurations utilizing this number of battery rows, and therefore isequally applicable to configurations utilizing a fewer number, or agreater number, of battery rows 405. Similarly, the design is notlimited to configurations in which each battery row is comprised ofsixteen batteries, rather the design may be used with configurationsusing a fewer number, or a greater number, of batteries 401 per batteryrow 405.

In the prior art configuration illustrated in FIG. 4, interposed betweenbattery rows 405 are linear bus bars 407, where each bus bar 407 isdevoid of the contact fingers utilized in the prior art approach shownin FIG. 3. It should be understood that bus bars 407 may utilize anon-linear configuration. For example, if each row of batteries 401 isarranged in a non-linear fashion, the bus bars may utilize a similarshape (e.g., the zig-zag arrangement disclosed in U.S. patentapplication Ser. No. 14/802,207). Bus bars 407 are preferably made ofcopper, although other suitable electrically conductive materials suchas aluminum may be used. Although this approach may utilize any batterytype that provides access to both terminals at a single end portion ofthe battery, in the illustrated assembly batteries 401 are cylindrical,preferably utilizing an 18650 form factor.

The batteries within a single row 405 form a group with all terminals ofa first polarity being electrically connected to a single bus bar on oneside of the battery row, and all terminals of the second polarity beingelectrically connected to a single bus bar on the other side of thebattery row. For example, all positive terminals of battery row 405A areelectrically connected to bus bar 407A and all negative terminals ofbattery row 405A are electrically connected to bus bar 407B. As a resultof this approach, each group of batteries represented by a single roware electrically connected in parallel while the battery rows within asingle module 400 are electrically connected in series. By varying thenumber of batteries within a single row, as well as the number of rowswithin a single module, the desired voltage and current capabilities ofthe module may be configured as desired to meet the design criteria fora specific application.

Preferably module 400 uses wire bond interconnects 409 to electricallycouple the batteries 401 to the bus bars 407. Wire bond interconnects409 may be attached using any wire bonding technique suitable for theselected wire gauge, wire material and bus bar material. Typical wirebonding techniques include, but are not limited to, bonding, resistancebonding, thermocompression bonding, thermosonic bonding and laserbonding.

As previously noted, module 400 may be configured as the entire batterypack. For some applications, however, multiple modules 400 may beelectrically interconnected in order to achieve the desired battery packoutput characteristics. For example, modules 400 may be electricallyinterconnected in series as illustrated in FIG. 5, or electricallyinterconnected in parallel as illustrated in FIG. 6. Otherseries/parallel arrangements may be used with the invention.

FIG. 7 provides a perspective view of a portion of a battery moduleutilizing the bus bar arrangement shown in FIG. 4. For clarity only aportion of the illustrated batteries shown in FIG. 7 are interconnectedto adjacent bus bars. This figure shows a clearer view of the accessapertures 701 fabricated into upper tray member 403, apertures 701allowing access to the battery terminals located at the ends of thebatteries. The access apertures 701 utilized in the illustratedembodiment are continuous slots that provide easy electrical access toall of the batteries within a single row while still holding thebatteries in place. Thus in this configuration there is a single accessaperture per battery group. It should be understood, however, thataccess apertures 701 may utilize an alternate shape and may beconfigured to allow access to more or less than a battery group. Forexample, the access apertures may be configured with a circular orelliptical shape with one opening per battery, or one opening persub-group of batteries (e.g., two or more batteries).

In the arrangement illustrated in FIG. 7, upper tray member 403, whichmay be molded, cast, printed using a 3D printer, or fabricated using analternate technique, is preferably fabricated from a plastic material(e.g., polycarbonate, acrylonitrile butadiene styrene (ABS),polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET),nylon, etc.), although other materials may also be used to fabricate thetray member. Preferably bus bars 407 are integrated into upper traymember 403, for example by molding the bus bars into the tray memberduring tray member fabrication. Alternately, bus bars 407 may be bondedinto slots that are molded into the upper tray member 403. Integratingthe bus bars into a member, such as the upper surface of tray member403, insures that the bus bars are properly positioned during thebattery interconnection process and that they remain in position afterpack fabrication, thus minimizing stress and damage to the batteryinterconnects.

Although the invention may use any of a variety of techniques toposition the batteries within the pack, or module, the prior artconfiguration illustrated in FIGS. 4 and 7 utilizes a lower tray member703, a battery separating member 705 and a heat spreader 707. Theseaspects are highlighted in FIGS. 7 and 8. It will be appreciated thatthe configuration of members 701, 703 and 705 assume the use ofcylindrical cells, and therefore the use of an alternate form factor forbatteries 401 would require the redesign of members 701, 703 and 705.Heat spreader 707 is fabricated from a thermally conductive material,such as aluminum, with a thermal conductivity of at least 100 Wm⁻¹K⁻¹.

Separating member 705 is fabricated from an electrically insulatingmaterial, preferably a plastic such as a polycarbonate, acrylonitrilebutadiene styrene (ABS), polypropylene (PP), polyethylene (PE),polyethylene terephthalate (PET), or nylon. Preferably member 705 isfabricated using an extrusion process, although alternate fabricationtechniques may be used such as molding, casting or printing using a 3Dprinter. In the illustrated configuration, each battery 401 is heldwithin its own cavity 801 within separating member 705. The walls 803 ofeach battery cavity 801 may utilize any of a variety of shapes, suchthat each cavity may have either a circular or a non-circularcross-section. Preferably and as illustrated, each battery cavity 801 isfabricated with a six-sided shape in which the six sides are of equallength (i.e., a six-sided, regular shape). Each wall 803 may bestraight; alternately, each wall 803 may be curved outwardly away fromthe cavity center line; alternately, each wall 803 may be curvedinwardly towards the cavity center line as shown.

Enclosing each battery within a six-sided, regular cavity, and morepreferably a six-sided, regular cavity in which the cavity walls 803curve inwardly towards the corresponding cavity center line as shown,provides several benefits. First, the cavities prevent the batteriesfrom accidentally touching one another, either during battery packfabrication and assembly or once the battery pack is installed. Assumingthat the battery pack is installed in an electric vehicle, separatingmember 705 also helps to prevent battery shorting if the battery pack isdamaged during a collision. Second, the use of a six-sided, regularcavity rather than a cavity with a circular cross-section simplifiesbattery pack assembly since the six-sided shape provides additionalfitting flexibility, thereby allowing the fabrication tolerances forboth the batteries and the separating member to be looser than wouldotherwise be required. Third, the air space provided by the six-sidedbattery cavities improves battery-to-battery thermal isolation. Fourth,the contraction and expansion that batteries often exhibit duringthermal cycling is more easily handled by a six-sided cavity rather thana circularly-shaped cavity. Fifth, the space between the corners of asix-sided cavity and a cylindrically-shaped battery provide ventingpathways if the battery vents through its side, for example during athermal runaway event.

FIG. 9 provides a top view of a portion 900 of a battery pack, orbattery pack module, configured in accordance with a preferredembodiment of the invention. Visible in this figure is the end portionof each of a plurality of batteries 401, where the batteries arepositioned to provide access to both a portion of the battery casing(e.g., casing crimp edge 901), which serves as one battery terminal(e.g., the negative battery terminal), and to the central batteryterminal nub 903, which serves as the second battery terminal (e.g., thepositive battery terminal). A separator 905 prevents battery casingsfrom touching adjacent casings, thereby insuring the desired level ofelectrical isolation between cells. Separator 905 may be comprised ofelectrically non-conductive filler, for example an electricallynon-conductive epoxy injected into the pack after the batteries areproperly positioned. Alternately separator 905, which may be similar tothe structure described above relative to assembly 400, can bepre-fabricated prior to battery insertion into the pack/module, forexample using a fabrication process such as molding, casting, extrusion,3D printing, etc., and comprised of a suitable electricallynon-conductive material such as plastic (e.g., polycarbonate,acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene(PE), polyethylene terephthalate (PET), nylon, etc.).

As shown in FIG. 9, battery pack/module 900 includes a plurality ofnon-overlapping bus bars 907 arranged in an alternating polarityconfiguration, where each of the bus bars includes multiple interconnectmounting platforms as described in detail below. In the exemplaryembodiment, bus bars 907 are of uniform thickness and fabricated from anelectrically conductive material such as aluminum or copper. Preferablybus bars 907 are interposed between every two rows of batteries 401 asshown (i.e., one bus bar per every two rows of batteries). Thus, forexample, the batteries within rows 909A and 909B form a first group ofbatteries and the batteries within rows 909C and 909D form a secondgroup of batteries. In this configuration all battery terminals of afirst polarity corresponding to one group of batteries and all batteryterminals of a second polarity corresponding to another group ofbatteries are electrically connected to a single bus bar. Therefore inFIG. 9 the casing battery terminals 901 (e.g., the negative polarityterminals) corresponding to battery rows 909A and 909B and the centralnub terminals 903 (e.g., the positive polarity terminals) correspondingto battery rows 909C and 909D are all electrically connected to bus bar907A. Using this connection configuration, each group of batteriesrepresented by two rows of batteries are electrically connected inparallel while the battery groups are electrically connected in series.By varying the number of batteries per battery group, as well as thenumber of battery groups within a single module (or pack), the desiredvoltage and current capabilities may be configured as desired to meetthe design criteria of the intended application.

In order to insure clarity, FIG. 9 does not show an electrical insulatorpositioned between bus bars 907 and batteries 401. It will beappreciated, however, that the bus bars cannot be allowed toinadvertently make electrical contact with either battery terminal.Accordingly, an electrically insulating layer is interposed between thebottom surface of bus bars 907 and the batteries. In one configuration,and as illustrated in FIG. 10, bus bars 907 are electrically isolatedfrom batteries 401 with an upper tray member 1001, where upper traymember 1001 is similar to previously described tray member 403. In orderto provide the desired electrical isolation, tray member 1001 isfabricated from an electrically insulative material such as a plastic(e.g., polycarbonate, acrylonitrile butadiene styrene (ABS),polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET),nylon, etc.), or the member is coated (e.g., at least the bottom surfaceof the tray member) with an electrically insulative material. Traymember 1001 includes a plurality of access apertures 1003 that provideaccess to the underlying battery terminals, thus allowing theinterconnect mounting platforms of the bus bars to be electricallyconnected to the battery terminals via a plurality of interconnects asdescribed below. Access apertures 1003 may be formed as continuousslots, as illustrated in FIG. 10, thereby providing easy electricalaccess to all of the batteries within two adjacent rows of batteries. Itshould be understood, however, that access apertures 1003 may utilize analternate shape (e.g., circular, elliptical, etc.) and may be configuredto allow access to more or less batteries than the access aperturesshown in FIG. 10. Bus bars 907 may be integrated into tray member 1001,for example by molding the bus bars into the tray member during traymember fabrication; alternately, bus bars 907 may be bonded into regionsmolded into the tray member 1001; alternately, bus bars 907 may bebonded or otherwise attached to the top surface of tray member 1001.Integrating or otherwise attaching bus bars 907 to member 1001 insuresthat the bus bars are properly positioned during the batteryinterconnection process, and that the bus bars do not move after batterypack fabrication as such movement would stress, and potentially damage,the battery interconnects.

FIG. 11 illustrates an alternate configuration for electricallyisolating bus bars 907 from the underlying batteries. As shown, anelectrical insulator 1101 is applied to the bottom surface of the busbars as well as the associated interconnect mounting platforms andcoupling segments described below. As with the approach describedrelative to FIG. 10, the approach used in this configuration not onlyprevents inadvertent shorting between the bus bars and the batteries,but also helps to stabilize the bus bars, thereby insuring proper busbar placement and minimal strain on the interconnects due to bus barmovement after pack fabrication. Preferably this approach uses a layerstacking fabrication technique, for example by stacking the bus barsonto an electrically insulating layer of resin impregnated fiberglass orother suitable electrically insulating material.

As shown in FIG. 9, extending from both edges of each bus bar 907 areelectrical coupling segments 911 and 913. More specifically, a firstplurality of electrical coupling segments 911, which extend from a firstedge of each bus bar 907, provides an electrical connection between eachcentral bus bar segment 907 and each corresponding interconnect mountingplatform 915. Similarly, a second plurality of electrical couplingsegments 913, which extend from a second edge of each bus bar 907,provides an electrical connection between each central bus bar segment907 and each corresponding interconnect mounting platform 917. In theillustrated embodiment, a third plurality of electrical couplingsegments 919 provides an electrical connection between seriallyconfigured interconnect mounting platforms 915 and 916 while a fourthplurality of electrical coupling segments 921 provides an electricalconnection between serially configured interconnect mounting platforms917 and 918. Note that in this embodiment, other than for platformlocation relative to a corresponding bus bar, mounting platforms 915-918are substantially equivalent.

Interconnect mounting platforms 915-918 have a larger width 923 than thewidth 925 of coupling segments 911 or the width 927 of coupling segments913 or the width 929 of coupling segments 919 or the width 931 ofcoupling segments 921. In the illustrated and preferred embodiment, thewidth 923 of each mounting platform 915-918 is between one third and onehalf the diameter 933 of battery 401, although it should be understoodthat the invention may use other platform widths. Preferablyinterconnect mounting platforms 915-918 have a substantially circularcross-section, circular except for the junction between the mountingplatform and the corresponding coupling segments as shown.

As described above, in the preferred embodiment there are two rows ofbatteries, also referred to herein as a battery group, per bus bar 907.The use of interconnect mounting platforms 915-918 provides a means ofachieving this configuration while minimizing bus bar current densityvariations and insuring that individual interconnect resistance remainsrelatively low and at about the same level per battery. For example inthe preferred embodiment, interconnect resistance is about 30% ofbattery internal resistance and the bus bar current density only variesby a factor of approximately two. As a result, variations in batteryaging and discharge rate are minimal.

Interconnect mounting platforms 915-918 simplify battery pack (ormodule) fabrication by providing large areas to which the batteryinterconnects are attached. Preferably the interconnects 935 thatelectrically couple terminals 901 and 903 of batteries 401 to bus bars907 via interconnect mounting platforms 915-918 are comprised of wirebonds. If desired, each wire bond interconnect may be comprised of afusible interconnect, i.e., an interconnect with a large enough diameterto allow it to carry the desired current while having a small enoughdiameter to insure that it will break when the desired current isexceeded by a preset amount. The wire bond interconnects may be attachedusing any wire bonding technique suitable for the selected wire gauge,wire material and bus bar material. Typical wire bonding techniquesinclude, but are not limited to, ultrasonic bonding, resistance bonding,thermocompression bonding and thermosonic bonding.

While wire bond interconnects offer a number of benefits, for examplethe ability to use the wire bond as a fusible link, this type ofinterconnect suffers from several drawbacks, the primary drawback beingthe time, and thus cost, required to couple the wire to the crimpedregion of the battery. This problem, which is common when the batterypack design requires that both interconnects be coupled to the topportion of the batteries, is due to the limited diameter of the wire andthe limited area offered by the crimped battery case (i.e., regions901). When coupling the wire to the crimped region of a battery, i.e.,the edge of the battery case, the pattern recognition system used in aconventional wire bonding machine may take longer than desired to alignthe wire with the crimped region due to the small feature sizes.Additionally, due to the limited bonding area, this bond may be moreprone to failure, potentially requiring re-bonding to correct the failedbond.

Due to the issues relating to attaching wire bond interconnects to thecrimped region of the battery casings, in at least one embodiment of theinvention ribbon interconnects (i.e., an interconnect with asubstantially rectangular cross-section) are used to couple therelatively small crimped edge region 901 of each battery 401 to thecorresponding mounting platform. Even though the crimped edge region 901of each battery 401 is relatively small and often includes sizevariations that result from the standard manufacturing tolerances usedby battery manufacturers, the large surface area offered by the ribboninterconnects allow these interconnects to be rapidly and efficientlybonded to the crimped edge of the corresponding battery casings. Theribbon interconnects, if used, may be attached using any conventionalfiber bonding technique suitable for the selected wire gauge, wirematerial and bus bar material. Exemplary coupling techniques includelaser welding (e.g., laser oscillation welding, laser micro welding),e-beam welding, resistance welding, ultrasonic bonding, thermosonicbonding, and thermocompression bonding. While ribbon interconnects mayalso be used to couple the battery terminal nubs 903 to thecorresponding mounting platforms, in at least one embodiment wire bondinterconnects are used for the battery terminal nubs 903 and ribboninterconnects are used for the battery crimped regions 901.

In the preferred and illustrated embodiment, a singular coupling segment911 provides the necessary electrical connection between the central busbar segment 907 and each of the corresponding interconnect mountingplatforms 915 connected to terminal nubs 903. In contrast, in thisembodiment a pair of coupling segments 913 provides the necessaryelectrical connection between the central bus bar segment 907 and eachof the corresponding interconnect mounting platforms 917 connected tocrimped battery case regions 901. The use of a pair of couplingsegments, rather than a single coupling segment, provides a large openregion 937, thereby increasing access to the underlying battery edge 901and simplifying the process of attaching interconnects to this region.

Preferably and as shown, each interconnect mounting platform 915-918 iscentered over the approximate center of the space (i.e., void) betweenthree adjacent batteries, where two of the three adjacent batteries ispreferably connected, via interconnects, to the mounting platform inquestion. This aspect of the preferred embodiment is illustrated in FIG.12, where FIG. 12 provides an enlarged view of section 939 of FIG. 9.For clarity, this figure only includes a single coupling segment 911 andthe corresponding interconnect mounting platforms 915A and 916A. Asshown in FIG. 12, and in accordance with the preferred embodiment of theinvention, the center of mounting platform 915A is positionedapproximately over the center of the space between batteries 401A-401Cand the center of mounting platform 916A is positioned approximatelyover the center of the space between batteries 401B-401D. By centeringthe mounting platform as described, each battery terminal (i.e., caseedge 901 or nub 903) is equally accessible during the interconnectattachment process, thus insuring that each interconnect can be properlyplaced and attached to the underlying battery terminal.

In order to minimize the potential for interconnect damage, preferablyeach interconnect mounting platform is rigidly fixed to an underlyingstructure. While the interconnect mounting platforms may be fixed to anelectrical insulator positioned between bus bars 907 and batteries 401,e.g., tray member 1001 or insulator 1101, preferably the interconnectmounting platforms are rigidly fixed to separator structure 905. Fixingeach mounting platform to separator 905 is preferred regardless ofwhether the separator is comprised of a filler or comprised of apre-fabricated structure, both of which are described above. Themounting platforms may be bonded, staked, clamped, pinned, or otherwisefixed to separator 905 (or to an electrical insulator such as members1001 and 1101). In the illustrated embodiment, each mounting platform915-918 includes a hole 941 that is preferably centered on thecorresponding platform. A heat stake 943 is then used to fix theplatform to separator 905. Rigidly fixing the mounting platforms to theseparator, or insulator, helps to minimize platform movement, therebyminimizing the potential for interconnect damage after battery packfabrication is complete and the pack is in use, for example as thebattery pack of an EV.

FIGS. 13-16 illustrate an alternate preferred embodiment of theinvention utilizing many of the design features of the previousembodiment. As shown in the top view of FIG. 13, batteries 401 aresituated as previously described, specifically positioned to provideaccess via one end to both terminals of each battery, e.g., casing crimpedge 901 and central battery nub 903. Accidental contact betweenbatteries is prevented using separator 905. Battery pack (or batterymodule) 1300 includes a plurality of non-overlapping bus bars 1301arranged in an alternating polarity configuration, where each of the busbars includes multiple interconnect mounting platforms as described indetail below. Bus bars 1301 are preferably fabricated from aluminum orcopper and are of uniform thickness.

Although pack/module 1300 can be configured to function with batterygroups of various sizes, the inventors have found that the optimalconfiguration interposes one bus bar 1301 between every two rows ofbatteries as shown. It should be understood, however, that the inventionmay use other sizes of battery groupings, for example interposing busbars between every three rows of batteries.

Extending at a non-perpendicular angle from both edges of each bus bar1301 are interconnect mounting platforms that are designed to simplifyinterconnect attachment procedures while minimizing bus bar currentdensity variations and insuring that individual interconnect resistanceremains relatively low and at about the same level per battery. Asvisible in the portion of the battery pack/module shown in FIG. 13, eachmounting platform 1303 extends at a non-perpendicular angle from theleft side of each bus bar 1301 and is arcuately shaped with a graduallydecreasing width. The shape of each mounting platform 1303 allows easyplacement and attachment of interconnects 1305 between the mountingplatform 1303 and four adjacent battery casing terminals 901. To achievethe same ease of interconnect attachment with the interconnects coupledto the central battery terminals (i.e., positive terminal nubs 903),each mounting platform 1307, which extends at a non-perpendicular anglefrom the right side of each bus bar 1301, includes a pair of platformextensions 1309 and 1310. As shown, each platform extension 1309 and1310 is an extension of a single platform portion 1311. The use of apair of platform extensions allows the mounting platform, and thus thebus bar, to connect to the furthest battery nubs (e.g., 903A and 903B)without requiring extended length interconnects. Preferably mountingplatform extensions 1309 and 1310 terminate in close proximity to therespective terminals to which they are to be attached.

In the preferred embodiment and as previously noted, each interconnectmounting platform is configured to be attached via interconnects to fourbatteries, with the four batteries contained in two different rows ofbatteries. As a result of this configuration, each mounting platformextends past the midpoint between adjacent bus bars, thereby causing themounting platforms from adjacent bus bars to be interspersed. Forexample in FIG. 13, plane 1313 is equidistant from bus bars 1301A and1301B. As shown, each mounting platform 1303 that extends away from busbar 1301A and towards bus bar 1301B extends past plane 1313 and,similarly, each mounting platform 1307 that extends away from bus bar1301B and towards bus bar 1301A extends past plane 1313.

For purposes of clarity, FIG. 13 does not show an electrical insulatorpositioned between bus bars 1301 and batteries 401. It will beappreciated, however, that the bus bars cannot be allowed toinadvertently make electrical contact with batteries 401, and morespecifically battery terminals 901 and 903. Accordingly, an electricallyinsulating layer is interposed between the bottom surface of bus bars1301 and the batteries. In one configuration, and as illustrated in FIG.14, bus bars 1301 are electrically isolated from batteries 401 with anupper tray member 1401, where upper tray member 1401 is similar topreviously described tray members 403 and 1001. In order to provide thedesired electrical isolation, member 1401 is fabricated from anelectrically insulative material such as a plastic (e.g., polycarbonate,acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene(PE), polyethylene terephthalate (PET), nylon, etc.), or the member orat least the bottom surface of the tray member is coated with anelectrically insulative material. Tray member 1401 includes a pluralityof access apertures 1403 that provide access to the underlying batteryterminals, thus allowing bus bar interconnect mounting platforms 1303and 1307 to be electrically connected to the battery terminals via aplurality of interconnects. Access apertures 1403 may be formed ascontinuous slots, as illustrated in FIG. 14, thereby providing easyelectrical access to the underlying batteries. It should be understood,however, that access apertures 1403 may utilize an alternate shape(e.g., circular, elliptical, etc.) and may be configured to allow accessto more or less batteries than the access apertures shown in FIG. 14.Bus bars 1301 may be integrated into tray member 1401, for example bymolding the bus bars into the tray member during tray memberfabrication; alternately, bus bars 1301 may be bonded into regionsmolded into the tray member 1401; alternately, bus bars 1301 may bebonded or otherwise attached to the top surface of tray member 1401.Integrating or otherwise attaching bus bars 1301 to member 1401 insuresthat the bus bars are properly positioned during the batteryinterconnection process, and that the bus bars do not move after batterypack fabrication as such movement would stress, and potentially damage,the battery interconnects.

FIG. 15 illustrates an alternate configuration for electricallyisolating bus bars 1301 from the underlying batteries. As shown, anelectrical insulator 1501 is applied to the bottom surface of the busbars as well as the associated interconnect mounting platforms. As withthe approach described relative to FIG. 14, the approach used in thisconfiguration not only prevents inadvertent shorting between the busbars and the batteries, but also helps to stabilize the bus bars,thereby insuring proper bus bar placement and minimal strain on theinterconnects due to bus bar movement after pack fabrication. Preferablythis approach uses a layer stacking fabrication technique, for exampleby stacking the bus bars onto an electrically insulating layer of resinimpregnated fiberglass or other suitable electrically insulatingmaterial.

The interconnects 1305 that are used to couple interconnect mountingplatforms 1303 to battery terminals 901 and to couple interconnectmounting platforms 1307 to battery terminals 903 preferably use wirebond interconnects as described above relative to the embodiment shownin FIG. 9. Alternately, or as a replacement for some of the wire bondinterconnects, the system may use ribbon interconnects. As noted above,the large surface area offered by ribbon interconnects makes themespecially useful in connecting to the crimped edge region 901 of eachbattery 401 due to the relatively small size of this region as well asvariations in this region's size due to manufacturing tolerances. Theinterconnects, i.e., wire bond and/or ribbon interconnects, may beattached using any conventional bonding technique suitable for theselected wire gauge, wire material and bus bar material. Exemplarycoupling techniques include laser welding (e.g., laser oscillationwelding, laser micro welding), e-beam welding, resistance bonding,ultrasonic bonding, thermosonic bonding, and thermocompression bonding.

In order to minimize the potential for interconnect damage, preferablyeach interconnect mounting platform is rigidly fixed to an underlyingstructure as in the prior embodiment. While the interconnect mountingplatforms may be fixed to an electrical insulator positioned between busbars 1301 and batteries 401, e.g., tray member 1401 or insulator 1501,preferably the interconnect mounting platforms are rigidly fixed toseparator structure 905. Fixing each mounting platform to separator 905is preferred regardless of whether the separator is comprised of afiller or comprised of a pre-fabricated structure, both of which aredescribed above. The mounting platforms may be bonded, staked, clamped,pinned, or otherwise fixed to separator 905 (or to an electricalinsulator such as members 1401 and 1501). In at least one configurationof the preferred embodiment illustrated in FIGS. 13-15, and as shown inthe detailed view of FIG. 16, each mounting platform 1303 and 1307includes an aperture 1601. A heat stake 1603, passing through aperture1601, is then used to fix the platform to separator 905. Rigidly fixingthe mounting platforms to the separator, or insulator, helps to minimizeplatform movement, thereby minimizing the potential for interconnectdamage after battery pack fabrication is complete and the pack is inuse, for example as the battery pack of an EV.

Systems and methods have been described in general terms as an aid tounderstanding details of the invention. In some instances, well-knownstructures, materials, and/or operations have not been specificallyshown or described in detail to avoid obscuring aspects of theinvention. In other instances, specific details have been given in orderto provide a thorough understanding of the invention. One skilled in therelevant art will recognize that the invention may be embodied in otherspecific forms, for example to adapt to a particular system or apparatusor situation or material or component, without departing from the spiritor essential characteristics thereof. Therefore the disclosures anddescriptions herein are intended to be illustrative, but not limiting,of the scope of the invention.

What is claimed is:
 1. A battery assembly, comprising: a plurality ofbatteries divided into rows, each battery of said plurality of batteriescomprising a first terminal at a first end portion of said battery and asecond terminal at said first end portion of said battery, wherein saidplurality of batteries are divided into a plurality of battery groups,wherein each battery group of said plurality of battery groups iscomprised of at least two of said rows, wherein said batteries withineach battery group are electrically connected in parallel, and whereinsaid battery groups of said plurality of battery groups are electricallyconnected in series; and a plurality of non-overlapping bus barsconfigured in an alternating pattern with said plurality of batterygroups, wherein said alternating pattern alternates a single bus bar ofsaid plurality of non-overlapping bus bars with a single battery groupof said plurality of battery groups, each single bus bar of saidplurality of non-overlapping bus bars comprising: a first plurality ofinterconnect mounting platforms extending at a first non-perpendicularangle from a first edge of said single bus bar, wherein each of saidfirst plurality of interconnect mounting platforms is arcuately shaped,wherein each of said first plurality of interconnect mounting platformsis electrically connected to a first subset of said plurality ofbatteries via said first terminals of said first subset of saidplurality of batteries, and wherein said first subset of said pluralityof batteries is comprised of at least four batteries of said pluralityof batteries; and a second plurality of interconnect mounting platformsextending at a second non-perpendicular angle from a second edge of saidsingle bus bar, wherein each of said second plurality of interconnectmounting platforms is comprised of an initial platform portion extendingfrom said second edge of said single bus bar and a pair of platformextensions extending from said initial platform portion, wherein saidinitial platform portion of each of said second plurality ofinterconnect mounting platforms is electrically connected to a secondsubset of said plurality of batteries via said second terminals of saidsecond subset of said plurality of batteries, wherein said second subsetof said plurality of batteries is comprised of at least one battery ofsaid plurality of batteries, wherein a first platform extension of saidpair of platform extensions is electrically connected to a third subsetof said plurality of batteries via said second terminals of said thirdsubset of said plurality of batteries, wherein said third subset of saidplurality of batteries is comprised of at least one battery of saidplurality of batteries, wherein a second platform extension of said pairof platform extensions is electrically connected to a fourth subset ofsaid plurality of batteries via said second terminals of said fourthsubset of said plurality of batteries, and wherein said fourth subset ofsaid plurality of batteries is comp iced of at least one battery of saidplurality of batteries.
 2. The battery assembly of claim 1, wherein saidfirst plurality of interconnect mounting platforms is fixed to anunderlying structure.
 3. The battery assembly of claim 1, wherein saidsecond plurality of interconnect mounting platforms is fixed to anunderlying structure.
 4. The battery assembly of claim 1, wherein saidfirst plurality of interconnect mounting platforms is fixed to anunderlying structure, and wherein said second plurality of interconnectmounting platforms is fixed to said underlying structure.
 5. The batteryassembly of claim 4, said underlying structure comprising an electricalinsulator positioned between said plurality of batteries and saidplurality of non-overlapping bus bars.
 6. The battery assembly of claim4, said underlying structure comprising a battery separator structure.7. The battery assembly of claim 4, further comprising a first pluralityof mounting apertures corresponding to said first plurality ofinterconnect mounting platforms and a second plurality of mountingapertures corresponding to said second plurality of interconnectmounting platforms, wherein said first and second pluralities ofinterconnect mounting platforms are fixed to said underlying structurevia said first and second pluralities of mounting apertures.
 8. Thebattery assembly of claim 4, wherein said first and second pluralitiesof interconnect mounting platforms are fixed to said underlyingstructure using a technique selected from bonding, staking, clamping andpinning.
 9. The battery assembly of claim 1, said first battery terminalof each battery of said plurality of batteries comprising a crimped edgeregion integral to a battery casing corresponding to each battery ofsaid plurality of batteries.
 10. The battery assembly of claim 1, saidsecond battery terminal of each battery of said plurality of batteriescomprising a terminal nub integrated into a central region of a batterycap assembly.
 11. The battery assembly of claim 1, said each single busbar of said plurality of non-overlapping bus bars further comprising: afirst plurality of wire bond interconnects, wherein each of said firstplurality of interconnect mounting platforms is electrically connectedto said first subset of said plurality of batteries by said firstplurality of wire bond interconnects; and a second plurality of wirebond interconnects, wherein each of said second plurality ofinterconnect mounting platforms is electrically connected to saidsecond, third and fourth subsets of said plurality of batteries by saidsecond plurality of wire bond interconnects.
 12. The battery assembly ofclaim 1, said each single bus bar of said plurality of non-overlappingbus bars further comprising: a first plurality of ribbon interconnects,wherein each of said first plurality of interconnect mounting platformsis electrically connected to said first subset of said plurality ofbatteries by said first plurality of ribbon interconnects; and a secondplurality of ribbon interconnects, wherein each of said second pluralityof interconnect mounting platforms is electrically connected to saidsecond, third and fourth subsets of said plurality of batteries by saidsecond plurality of ribbon interconnects.
 13. The battery assembly ofclaim 1, said each single bus bar of said plurality of non-overlappingbus bars further comprising: a first plurality of ribbon interconnects,wherein each of said first plurality of interconnect mounting platformsis electrically connected to said first subset of said plurality ofbatteries by said first plurality of ribbon interconnects; and a secondplurality of wire bond interconnects, wherein each of said secondplurality of interconnect mounting platforms is electrically connectedto said second, third and fourth subsets of said plurality of batteriesby said second plurality of wire bond interconnects.
 14. The batteryassembly of claim 1, further comprising an electrical insulatorpositioned between said plurality of batteries and said plurality ofnon-overlapping bus bar.
 15. The battery assembly of claim 14, saidelectrical insulator comprising a tray member, said plurality ofnon-overlapping bus bars attached to an upper surface of said traymember, said tray member further comprising a plurality of apertures,wherein said plurality of apertures provide access to said firstterminal and to said second terminal of each battery of said pluralityof batteries.
 16. The battery assembly of claim 14, wherein saidelectrical insulator is comprised of an electrically insulutivc layerattached to a lower surface of at least a portion of said plurality ofnon-overlapping bus bars.
 17. The battery assembly of claim 1, whereinsaid plurality of non-overlapping bus bars are of approximately uniformthickness.